Member of the sikimensis species group (Zagorodnyuk, 1990). Ellerman (1941, 1947b, 1961) and Ellerman and Morrison-Scott (1951) listed irene as a valid species, but Weigel (1969) allocated it to Pitymys sikimensis as did Corbet (1978c), citing Gruberís (1969) "detailed study" as substantiation. However, the union of irene and sikimensis is insufficiently demonstrated by Gruberís study, whose data actually underscore the trenchant differences in size and dentition between the two. Ellerman (1947b, 1961) highlighted these marked differences in body size and m1 patterns in his keys and descriptions, contrasts reinforced by Feng et al. (1986), who recorded irene from NE Tibet and sikimensis just to the west, without evidence of character overlap. Lawrence (1982) recorded localities and habitat information for a large AMNH series of N. irene collected in Qionglai Shan (2900-3660 m), Sichuan.